Among developers of personal computer or workstation software, it is increasingly important to provide a flexible software environment while maintaining consistency in the user's interface. Interrupt processing on existing systems does not provide multi-level interrupt dispatchers. Multi-level interrupt dispatchers refer to interrupt handlers that also dispatch other interrupt handlers in a recursive manner.
For example, the Apple Macintosh computer has an interrupt handler that dispatches each interrupt handler in an iterative manner for the particular card as it interrupts the system. IBM processors, similarly, distribute all the device interrupts to a single level of interrupt dispatcher. Most of the computer industry follows the IBM model for processing interrupts.